Familial Chylomicronaemia Syndrome is an ultra-rare condition that affects 1 to 2 in a million of the population. It is also known Lipoprotein Lipase Deficiency (LPLD), Fredrickson Type 1, Hyperlipoproteinemia, and Familial Hyperlipidemia
People with the condition have difficulty properly digesting certain fats because they lack or have limited amounts of the enzyme lipoprotein lipase, or what they do have doesn’t work.. This results in a massive accumulation of fatty droplets called chylomicrons in the circulation. The presence of chylomicrons after fasting for 12-14 hours is associated with high levels of triglycerides. Triglycerides are the biomarker for the condition, meaning that high triglycerides in the blood indicate there is a problem with fat metabolism and can alert professionals to FCS. Triglycerides are measured in a simple fasting blood test.
If too much fat is eaten it does not get cleared from the body and instead travels round in the blood creating its creamy appearance which is typical of the condition. There is no treatment currently available to reduce triglyceride levels. Instead, patients are advised to eat less than 20g fat per day and avoid simple sugars and alcohol.. Many patients report that to be symptom free they need to eat no more than 10g fat per day. There is a section on how to approach living within these restrictions at ‘‘Living with FCS’
The photo shows 1ml of blood from a young boy with FCS, His triglyceride levels are 116.7 mmol/L. The creamy white appearance of the blood is the fat that his body has not ben able to remove. The normal range of triglycerides is below 2 mmol/L.
What causes Familial Chylomicronaemia Syndrome?
Five genes have so far been discovered which can cause the lack of ability to digest fat (and it is anticipated that more will be found in the future). Some of the genes that are known to cause Famial Chylomicronaemia Syndrome include those for familial lipoprotein lipase (LPL) deficiency, apolipoprotein C-II (APO C-II) deficiency or mutations that affect APOA5, GP1HBP1 and LMF1 genes.(1)(2)
The lipoprotein lipase gene is the most prevalent, present in around 80% of people with FCS.
How do you get Familial Chylomicronaemia Syndrome?
FCS is a recessive genetic disorder meaning that the patient has to inherit one faulty gene from both of his or her parents. The parents could have FCS themselves or be ‘carriers’. Carriers have one faulty gene and one functional gene and mostly appear unaffected. However, there is a possibility that there can be effects in later life for some carriers. The inheritance pattern is illustrated in the image below.
FCS affects men and women equally (although its impact is arguably greater on women) and there seems to be no ethnic bias, however there are a greater proportion of patients in Quebec, Canada due to the ‘founder effect’ The founder effect is where early settlers to the area carried the faulty gene and due to marriage within the community increased the presence of the faulty gene. Here in the UK there are clusters of patients from the South Asian community for the same reason.
Here is a short video explaining autosomal recessive inheritance from the NHS Genomics Education Programme
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